LTC2995

14

2995f

APPLICATIONS INFORMATION

1.8V – VT2

In the Temperature Monitor example discussed earlier with

thresholds at VT1 = 60°C and VT2 = 90°C and a desired

1.332V

10μA

= 133.2k

1.452V – 1.332V

10μA

= 12k

1.8V – 1.452V

10μA

= 34.8k

Voltage Monitoring

In addition to temperature measurement, the LTC2995

features a low power dual voltage monitoring circuit. Each

voltage monitor has two inputs (VH1/VL1 and VH2/VL2)

for detecting undervoltage and overvoltage conditions. If

either VH1 or VH2 falls below 0.5V (typical), the LTC2995

communicates an undervoltage condition by pulling UV

low. Similar, an overvoltage condition is flagged by pulling

OV low if either VL1 or VL2 rises above 0.5V.

When configured to monitor a positive voltage Vn using

the 3-resistor circuit configuration shown in Figure 5,

the resistive divider.

Voltage Monitor Design Procedure

The following 3-step design procedure selects appropriate

resistances to obtain the desired UV and OV trip points

for the voltage monitor circuit in Figure 7.

overvoltage monitor:

0.5V

•

(1)

trip point for the undervoltage monitor:

0.5V

•

(2)

(3)

Voltage Monitor Example

A typical voltage monitor application is shown in Figure 2.

The monitored voltage is a 5V ±10% supply. Nominal

current in the resistive divider is 10μA.

0.5V

10μA

•

5V

5.5V

≈ 45.3k

Figure 7. 3-Resistor Positive UV/OV Monitoring

+

LTC2995

2995 F07